U.S. patent number 6,365,875 [Application Number 09/498,174] was granted by the patent office on 2002-04-02 for heatable steering wheel.
This patent grant is currently assigned to TRW Automotive Safety Systems GmbH & Co. KG. Invention is credited to Martin Kreuzer, Michael Lehmann.
United States Patent |
6,365,875 |
Kreuzer , et al. |
April 2, 2002 |
**Please see images for:
( Certificate of Correction ) ** |
Heatable steering wheel
Abstract
A heatable steering wheel with electric heating wires on a wheel
rim is provided. The heating, wires are covered by a casing. The
casing consists of a support layer that has good thermal
conductivity and of an externally applied layer of veneer wood.
Inventors: |
Kreuzer; Martin
(Kleinwallstadt, DE), Lehmann; Michael
(Aschaffenburg, DE) |
Assignee: |
TRW Automotive Safety Systems GmbH
& Co. KG (Aschaffenburg, DE)
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Family
ID: |
8069000 |
Appl.
No.: |
09/498,174 |
Filed: |
February 4, 2000 |
Foreign Application Priority Data
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Feb 5, 1999 [DE] |
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299 02 044 U |
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Current U.S.
Class: |
219/204;
428/66.6; 74/552 |
Current CPC
Class: |
B62D
1/06 (20130101); B62D 1/065 (20130101); Y10T
428/218 (20150115); Y10T 74/20834 (20150115) |
Current International
Class: |
B62D
1/06 (20060101); B62D 001/06 () |
Field of
Search: |
;428/66.6 ;219/204
;74/552 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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3438266 |
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May 1985 |
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DE |
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3906576 |
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Jun 1990 |
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DE |
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0985590 |
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Mar 2000 |
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EP |
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10287247 |
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Oct 1998 |
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JP |
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Primary Examiner: Thomas; Alexander S.
Attorney, Agent or Firm: Tarolli, Sundheim, Covell, Tummino
& Szabo L.L.P.
Claims
What is claimed is:
1. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casing covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, and wherein said support
layer consists of a plastic reinforced with fibers, said heating
wires being embedded in a fleece layer.
2. The steering wheel according to claim 1, wherein said fleece
layer is made of one of the following: polyester, polyamide,
polypropylene and sisal.
3. The steering wheel according to claim 1, wherein materials
selected from one of: molybdenum disulfide, carbon black, metal
particles, or metal fibers are incorporated in the support
layers.
4. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casting covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, and wherein said support
layer consists of a laminated structure of glass fiber layers and
wood layers.
5. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casing covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, and wherein said support
layer consists of a material selected from the following: ABS,
polycarbonate, polyamide, said heating wires being embedded in a
fleece layer.
6. The steering wheel according to claim 5, wherein said fleece
layer is made of one of the following: polyester, polyamide,
polypropylene and sisal.
7. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casing covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, and wherein said support
layer consists of glass fibers impregnated with one of the
following: melamine resin, epoxy resin and polyester resin, said
heating wires being embedded in a fleece layer.
8. The steering wheel according to claim 7, wherein said fleece
layer is made of one of the following: polyester, polyamide,
polypropylene and sisal.
9. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casing covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, and wherein said support
layer consists of glass fibers impregnated with one of the
following: melamine resin, epoxy resin and polyester resin, the
glass fibers being provided in the form of a fleece layer.
10. A heatable steering wheel having a wheel rim, electric heating
wires arranged on the wheel rim and a casing covering the heating
wires, wherein said casing consists of a support layer and of an
externally applied layer of veneer wood, the casing with the
support layer and the veneer wood being provided as a pair of
prefabricated half shells bonded to each other, the support layer
being a laminated structure of glass fiber layers and wood layers.
Description
The present invention relates to a heatable steering wheel with
electric heating wires arranged on a steering wheel rim and a
casing covering the heating wires.
BACKGROUND OF THE INVENTION
Within attempts to improve comfort for motor vehicle users, inter
alia heatable steering wheels have been offered, in order to be
able to bring the most important grip region of the steering wheel,
i.e. the steering wheel rim, to a haptically pleasant temperature
as quickly as possible. As quickly as possible means, here, quicker
than is possible with the conventional heating devices for the
interior of motor vehicles. The heating wires can be connected with
the electrical supply system of the motor vehicle via the ignition
switch of the motor vehicle or in a preprogrammed manner, the
heating output being monitored and regulated in a known manner
using temperature sensors.
The steering wheel casing in such heatable steering wheels
frequently consists of leather which is placed around the steering
wheel rim over the heating wires and is sewn along an edge. One can
also arrange leather strips, provided with heating wires, on the
steering wheel rim and sew them to each other along an edge. The
leather casing here has the purpose of concealing the heating wires
visually, of protecting the hands of the motor vehicle user from a
direct contact with the heating wires which are heated to 60 to
70.degree. C. and to distribute the heat, emitted from the heating
wires, to greater surface regions. It is obvious that between the
latter functions and the basic problem of providing a pleasantly
tempered steering wheel as quickly as possible, a contradiction
exists for which there can be no optimum solution but rather only a
compromise matched to the respective case of application.
In top class vehicles, for which so-called wooden steering wheels
are offered to an increasing extent, hitherto an acceptable
compromise has been missing for the arrangement of heating wires.
In steering wheels in which the metallic steering wheel skeleton
has a casing of solid wood in the rim area, the arrangement of
heating wires is not possible. "Wooden steering wheels", however,
are also understood to mean embodiments in which the steering wheel
skeleton is encased with half shells of laminate wood in the rim
area, onto which a layer of veneer wood is applied externally, For
reasons of manufacturing technique, such half shells together with
the externally applied veneer wood must have a wall thickness of at
least 3 mm, which owing to the poor thermal conductivity of the
wood is too much for the rapid heating of the steering wheel rim
which is aimed for. With heating wires arranged beneath a wood
layer at least 3 mm thick, the outer layer of the steering wheel
rim can scarcely be brought more quickly to the desired temperature
than is possible via the conventional heating arrangements for the
interior of the vehicle. For these reasons, "heatable wooden
steering wheels" have hitherto not been developed and offered.
BRIEF SUMMARY OF THE INVENTION
The invention overcomes the above-mentioned difficulties and
proposes a "heatable wooden steering wheel" in which the surface of
the steering wheel rim can be brought to a haptically pleasant
temperature at a similar speed to steering wheel rims encased in
leather.
According to the invention the steering wheel casing consists of a
support layer having good thermal conductivity and of a layer of
veneer wood lying externally and connected with the support
layer.
Hitherto, one proceeded from the assumption that the arrangement of
veneer wood in the area of the steering wheel rim requires a
support layer of wood, because otherwise a sufficient adhesive
strength could not be achieved between the support layer and the
externally applied veneer wood. However, it has been found that
veneer wood can also be reliably connected with support layers
which consist of material having good thermal conducting properties
and which with a desirable small thickness for the passage of heat
have a sufficient mechanical strength. According to the invention,
the support layers preferably consist of glass fiber-reinforced
plastic, into which in addition materials having good thermal
conducting properties such as molybdenum disulphide and carbon
black are embedded.
BRIEF DESCRIPTION OF THE DRAWINGS
Further details of the invention are explained more closely with
reference to the drawings. In the drawings:
FIG. 1 shows a cross-section through a steering wheel rim according
to a first embodiment;
FIG. 2 shows a cross-section through a steering wheel rim according
to a second embodiment; and
FIG. 3 is a perspective view showing the structure of the steering
wheel rim
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the diagrammatic sectional illustration of FIG. 1, not to scale
with regard to the wall thickness, the steering wheel rim consists
of a metallic steering wheel skeleton 7 which is coated in a known
manner with a foam plastic, preferably of polyurethane on of an
expandable polypropylene. On this base steering wheel rim 6, 7 a
fleece layer 4 is arranged, which serves for fixing the heating
wires 3. Then following the heating wires 3 to the exterior is the
support layer 2 of glass fiber-reinforced plastic, and finally the
outermost layer of veneer wood, designated by 1. In the illustrated
example embodiment, the casing for the steering wheel rim 6, 7
including the heating wires 3 and the fleece layer 4 consists of
prefabricated half shells, which are glued to each other along the
joint surfaces 5.
The same reference numbers are used for the embodiment according to
FIG. 2. This embodiment differs from that according to FIG. 1 in
that the heating wires 3 are applied directly on the base steering
wheel rim 6, 7 and are fixed by means of the fleece layer 4. The
steering wheel casing consists in turn of prefabricated half shells
which here, however, only surround the support layer 2 and the
layer of veneer wood 1 lying externally and are glued or bonded to
each other along the joint surfaces 5. The embodiment according to
FIG. 2 has an advantage in that the heating wires are not
distributed onto two half shells and do not have to be connected in
a relatively costly manner with the electrical mains power supply,
but rather as a whole are arranged directly on the steering wheel
rim 6, 7 and are able to be wired more simply. On the other hand,
the externally applied fleece layer 4 for fixing the heating wires
3 forms an additional thermal conductivity resistance.
Tests have shown that with the structure of the steering wheel
casing according to the invention, heating-up times can be achieved
which are comparable with those of the heatable steering wheels
encased with leather, because the thermal conductivity of the
support layer according to the invention is substantially better
than that of wood previously used. In any case, through a suitable
selection of material and measurement of the thickness soft the
support layers for the steering wheel rim, heating-up times can be
achieved which are substantially lower than if the steering wheel
had to be heated up via the heating devices for the interior of the
motor vehicle.
The following materials are preferred for the support layer 2: ABS
(acrylnitride butadiene styrene copolymers), polycarbonate,
polyamide, preferably each with a fiber glass reinforcement. Glass
fibers impregnated with melamine resin, epoxy resin or polyester
resin can be used as well. A laminated structure of glass fiber
layers and wood layers may also be appropriate.
To improve the thermal conductivity of the support layer 2, the
layer is charged with materials such as molybdenum disulphide,
carbon black or metallic particles or fibers.
The fleece layer preferably consists of polyester, polyamide,
polypropylene or sisal fibers.
The heating wires 3 are preferably produced from alloys such as
CuNi and CrNi.
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